CINCINNATI—The Miami Dolphins' running game stalled the past two weeks as Reggie Bush continued to be hampered by a lingering knee bruise. Now they may have to be worried about a concussion problem for their No. 2 back, Daniel Thomas.

Thomas, who scored his second touchdown of the season in Sunday's win over Cincinnati and is the Dolphins' main short-yardage back, left with about seven minutes left in the fourth quarter and was tested for a concussion. The extent of Thomas' injury is unclear, and he was not seen in the locker room after the game.

Miami's No. 2 running back, Daniel Thomas, left with seven minutes left and was tested for a concussion. (AP Photo)

Bengals linebacker Ray Maualuga, who delivered the hit, was also removed from the game and tested for a concussion.

Thomas, the Dolphins' second-round pick in 2011, suffered a concussion in Week 1, which kept him out of the next game. He said earlier this season that he does not have a history of concussions, and he felt like he could have played in Week 2 against Oakland.

Thomas has 36 carries for 113 yards (3.1 average) and two touchdowns this season. If he can’t play next Sunday against the St. Louis Rams, fullback Jorvorskie Lane, who has two touchdowns this season, would become the Dolphins' primary short-yardage back.

On Sunday, Lane fumbled the ball away on his first carry and was stuffed on 4th-and-1 on his second attempt. Rookie Lamar Miller, who did not have a carry against the Bengals, likely would see more playing time if Thomas can’t play.